A statement posted on the ministry's website said one of the patients is a 67-year-old woman in Riyadh, who had been suffering from various chronic diseases. She is now under intensive care, receiving the health care and proper treatment.

The two other cases are both women health workers, one of them living in Asir region and the other in Riyadh. "They have mild symptoms but their health status are stable," said the MOH.

The new cases bring to 92 the total number of people who have contracted the virus worldwide, including 71 in Saudi Arabia.Of the 92 cases registered with the World Health Organization since last year, 46 have died, including 39 in Saudi Arabia.

The latest MERS death in the Kingdom, announced by the Ministry of Health on July 25, was an 83-year-old man in Asir.Unpredictable and deadly

Saudi and UK scientists studying MERS said the coronavirus is more deadly, unpredictable and has significant differences from severe acute respiratory syndrome (SARS) virus that erupted in Asia in 2003 and infected 8,273 people, nine percent of whom died.

Ziad Memish, Saudi deputy minister for public health, earlier said: “MERS coronavirus appears to be more deadly, with 60 percent of patients with co-existing chronic illnesses dying, compared with the one-percent toll of SARS.”

He said that the MERS infecting humans is unpredictable because the source of the virus is not yet known. While sharing clinical similarities with the SARS-like fever, cough and incubation period, he said there are also some important differences such as the rapid progression to respiratory failure of up to five days. The progression occurs earlier than in SARS.

In a Lancet Infectious Diseases publication, Saudi and UK scientists also noted a trend of older patients with more men and patients with underlying medical conditions succumbing to the disease.